In an attempt to increase overall functionality, there may be a desire to implement a wireless communications device capable of transmitting and receiving using multiple wireless communications standards or a single wireless communications standard that transmits and receives over several different frequency bands. Such a wireless communications device may enable communications with a larger number of communications devices. The use of multiple frequency ranges may also lead to fewer conflicts (e.g., transmission collisions) due to a spreading of transmissions over the multiple frequency range. Each wireless communications standard supported by the wireless communications device may require its own set of hardware and software. Furthermore, the use of multiple frequency bands may further increase hardware requirements.
To increase the data rate of wireless communications devices, some wireless communications standards may allow for the transmitting and receiving of multiple independent data streams, with each independent data stream requiring its own antenna. For example, a wireless communications device transmitting and receiving three independent data streams will require at least three transmit antennas and three receive antennas.
Additionally, some wireless communications devices may make use of what is known as transmit and/or receive diversity. Transmit and/or receive diversity is when more antennas than needed are used to transmit and/or receive independent data streams. For example, a wireless transmitter may use three transmit antennas to transmit two independent data streams, where the wireless transmitter is required to use only two transmit antennas to transmit the two independent data streams. A wireless receiver may use two receive antennas to receive one data stream, where the receiver is required to use only one receive antenna to receive one data stream.
A communications device may be referred to as an N×M communications device, wherein N is the number of transmit antennas and M is the number of receive antennas, with N and M being integer numbers ranging from one (1) and up. When both N and M are greater than one (1), the communications device may be referred to as being a multiple input, multiple output (MIMO) communications device. MIMO communications systems are one example of wireless communications systems implementing both transmit and receive diversity.
Therefore, a communications device that is compliant to two or more wireless communications standards, each potentially capable of communicating using multiple independent data streams as well as transmit and/or receive diversity and over multiple frequency bands, may have a significant amount of hardware that may greatly increase its size, complexity, and cost.
FIG. 1 illustrates a communications network 100 including an access point 105, a first communications device “communications device 1” 110, a second communications device “communications device 2” 115, and a third communications device “communications device 3” 120. The access point 105 may be a special form of communications device, providing other communications device connectivity to other network resources, such as the Internet, proprietary networks, data servers, multimedia servers, and so forth.
The access point 105 may be capable of communicating using several different wireless communications standards. For example, the access point 105 may communicate with the first communications device 110 using a first wireless communications standard, the second communications device 115 using a second wireless communications standard, and the third communications device 120 using a third wireless communications standard. The first wireless communications standard and the third wireless communications standard may be compatible wireless communications standards and the access point 105, the first communications device 110, and the third communications device 120 may form a first wireless network 125. The second wireless communications standard may be incompatible with either the first wireless communications standard or the third communications standard and therefore, the access point 105 and the second communications device 115 may form a second wireless network 130 that is incompatible with the first wireless network 125.
Alternatively, the first wireless communications standard, the second wireless communications standard, and the third communications standard may be compatible with each other, but the first wireless communications standard and the third wireless communications standard transmits and receives over a first frequency band, while the second wireless communications standard transmits and receives over a second frequency band.
If the first wireless network 125 and the second wireless network 130 operate on different operating frequencies, then the access point 105 may not be able to share components, such as filters, switches, and so forth. Antennas may be shared but a more expensive antenna may be required.